Genetic test and technologies

Question 1

Types of genetic test:

Answer 1

• Diagnostic
• Predictive
• Carrier
• Prenatal
• Preimplantation genetic diagnosis
• Screening
• Susceptibility
• Paternity test
• Genetic finger printing test

Question 2

Roles of genetic test:

Answer 2

• Confirm a clinical diagnosis
• Give information about prognosis
• Inform management
• Pre-symptomatic/predictive testing in close relatives
• Carrier testing
• Give accurate recurrence risks
• Prenatal diagnosis

Question 3

Explain diagnostic test:

Answer 3

• Patient has signs and symptoms suggesting a particular diagnosis
• A molecular genetic test will confirm a diagnosis
• In this context a genetic test is being used to confirm a clinical diagnosis.

Question 4

Explain predictive testing:

Answer 4

• Testing health of at-risk family members for a previously identified familial variant – often dominant

Question 5

Explain carrier testing:

Answer 5

• Autosomal recessive and X-linked disorder
• Testing an individual in isolation not particularly helpful good for couple testing
• Reproductive decision making

Question 6

Explain pre natal test:

Answer 6

• Genetic test performed in pregnancy where there is a increased risk of a specific condition affecting the fetus
• Involves chorionic villous sample or amniocentesis
• Often chromosomal or DNA if specific variant in the family has been identified
• Counselling issues

Question 7

Explain preimplantation genetic diagnosis:

Answer 7

Cell removed from embryo under gentle suction pipette for analysis.

Question 8

Explain genetic screening:

Answer 8

Target population, not high risk families
E.g. Newborn screening for Cystic fibrosis
It may be the same test but the context is different

Question 9

What is Sanger sequencing?

Answer 9

• Uses PCR to amplify regions of interest followed by sequencing of products
• Useful for single gene testing

Question 10

What is next generation sequencing?

Answer 10

• High throughput or massively parallel sequencing
• Can sequence whole human genome in one day
• Multi-gene panels, whole exome / genomes

Question 11

What is NGS data analysis:

Answer 11

• Generates millions of short DNA fragments (reads) the need to be filtered for quality and aligned to a reference sequence.
• Reference genome
• Identify variants
• Interpret variants